key remote not working

[Qsilver7]

Originally Posted by stackz

ok, so about 2 weeks ago the key remote on my normal use key (backup key has been dead since I bought the vehicle) stopped working. well, every now and then if I just press the key and keep it pressed while standing next to the vehicle, it will unlock or lock. I was thinking the battery finally wore out in it. it is an 01 x5 after all. battery is like 16 years old as this point.

I looked at videos on youtube about battery replacement and so I took backup remote since I knew its battery was dead and cut it open and replaced it with a brand new non-rechargable battery (there's several videos where people do this actually). I can still manually lock/unlock the vechicle and start it with this key but even with the new battery in it, the remote features dont work.

is it because this one has been dead for so long that the chip wont transpond or should I just buy a new oem battery for it. I will say that I dont have it sautered in place, just sitting in the electronic portion of the key. but I even had this section just sitting in my hand and using one hand to press it together for good contact while using the other one to press the buttons, got nothing.

I hear people talking about some sort of radio antenna in the cars that will go bad and stop the remotes from working but...if this went bad, wouldnt the radio itself have bad reception?

just trying to get this sorted out before we have our first child next month as it will be a pain in the ass to manually lock/unlock the vehicle in july heat with a baby in a carseat lol.

Although the radio antennas and amps that boosts and sends that data to the audio system are in close proximity to each other...they do run to their respective modules. So one doesn't necessarily depend on the other to operate.

The FBZV & DWA (remote central locking & anti-theft alarm siren) systems do not use a "transponder". The remote key transmits a 315 MHz radio signal which is picked up by the antenna in the rear left cargo window...then sends that data to a receiver in the tailgate. From there...the data is sent up to the GM where the GM sends a command to FZV (central locking) to lock/unlock the vehicle...and to DWA (alarm siren system) to arm/disarm the vehicle.

Both of these systems (FZV & DWA) are independent but work in conjunction with each other. The EWS system is also independent of these two systems and it is the one that uses the transponder in the key. And it does NOT require the battery inside the key...it uses induction to self power itself.

If your remote key is sending the correct RF (radio frequency) for your location (315 MHz in No America...433 Mhz in Europe)...the issue could be some other component that is responsible for getting the command to the GM to lock/unlock & arm/disarm the vehicle.

The Touring (wagon), and SAV/SUVs use a similar antenna set-up...you can see the FZV antenna in the left rear cargo window in the illustration of an e39 Touring below. The FZV antenna for your e53 is in the same location:

You can see in the illustration below of the P-bus...were the GM is the main control module for that bus...and that FBZV & DWA receives their comands from the GM:

The info below shows the e53's remote key receiver and amp which is located in the upper part of the tailgate:

{the diagram below shows how the various cables run from the multiple amps & receivers...to the different modules and systems}

Single parts f antenna-diversity | BMW X5 E53 X5 4.4i N62 USA